The primary objective of this study is to describe the safety and tolerance of synagis, compared with placebo, in children below or equal to 2 years of age with Cystic Fibrosis. The secondary objectives of this study relate to both short term and long term outcome variables. They will describe the incidence of RSV hospitalization, total days of RSV hospitalization, use of O2 for RSV, ICU admission for RSV, mechanical ventilation for RSV. To evaluate at 6 months weight gain, changes in use of pulmonary medications from baseline, incidence of pseudomonas bacterial colonization, incidence of documented wheezing episodes, and total days of steroid usage. The hypothesis is that Synagis will be tolerated in patients 2 years of age or below safely.